A team of Japanese researchers has achieved something incredible: they've captured, for the first time ever, a movie which shows how thoughts form in the brain.

OK, so it's a thought forming in the brain of a zebrafish. And OK, its the fish's reaction to seeing food, so it's probably along the lines of "HUNGRY!". But we shouldn't play this down: this is a fundamental leap forward in our understanding of how brains work.

The researchers used a new technique to record the footage: a super-sensitive fluorescent probe that detects neuron activity. That lets us see neurons glowing when they're active—and the cascade of light you see in this video, first published in Current Biology, is the neuronal response of a zebrafish responding to the presence of its prey. In other words, you're seeing what the fish thinks when it sees its lunch.

Clearly zebrafish aren't the brainiest creatures in the world, but that's why the researchers from Japan's National Institute of Genetics are now working out how to use the technique in other creatures—and get a better insight into how our brains really work. [Current Biology via Geekosystem]